Ache

Ache \eyk\ , verb;
1. To have or suffer a continuous, dull pain
2. To feel great sympathy, pity, or the like
3. To feel eager; yearn; long
noun;
1. A continuous, dull pain

Me, for the last three days (source)

The origin of ache is Old English acan ("to ache, suffer pain") from Proto-Germanic *akanan, which is probably derived from the Proto-Indo-European base *ag-es- ("fault, guilt"). *Ag-es- and similar phonemes in Sanskrit and Greek may be onomatopoeic from the sound of groaning. The noun form comes from Middle English æche from Old English æce. Æche derived from Proto-Germanic *akiz, which is directly related to *akanan.

The spelling differences between the noun and verb forms reflected a difference in pronunciation. The noun was pronounced like modern ache, but the verb form had a soft \a\ and the 'ch' sounded like it does in watch ([ɑtʃ] if you know IPA). By the 1700's the two forms had the same pronounciation, and the spelling of both changed to ache based on a false assumption that their origin was Greek akhos ("pain, distress").